A Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of RO7303509 in Participants With Systemic Sclerosis

A Phase Ib, Double-Blind, Randomized, Placebo-Controlled, Multicenter Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of Multiple-Ascending Doses of RO7303509 in Participants With Systemic Sclerosis

The purpose of this study is to evaluate the safety, tolerability, and pharmacokinetics (PK) of RO7303509 treatment in participants with systemic sclerosis (SSc) during a multiple-ascending-dose (MAD) portion of the trial. In the MAD phase, increasing doses of study drug will be tested sequentially. For each dose tested, the MAD stage will consist of a treatment period of 12 weeks followed by either a safety follow-up period of 13 weeks or continued treatment in an optional open-label safety extension (OSE) stage of 52 weeks to assess the long-term safety. All patients in the OSE stage will receive RO7303509 and no patient will receive placebo.

Inclusion Criteria:

Inclusion Criteria for the MAD Stage:

• Weight of 45-150 kg at screening
• Diagnosis of SSc, as defined by 2013 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria and ≤ 10 years disease duration from first non-Raynaud's symptom
• Agreement to remain abstinent or use an effective contraceptive method among males and females with childbearing potential for 4 months after last dose of study drug

Inclusion Criteria for the OSE Stage:

• No clinically significant change in eligibility status
• Completion of the MAD and ability to roll over into the OSE within 5 days

Exclusion Criteria:

• Active rheumatic autoimmune disease other than SSc requiring treatment with disease-modifying therapy
• Pulmonary disease with forced vital capacity (FVC) ≤ 50% of predicted
• History or clinical manifestations of significant metabolic, hepatic, renal, pulmonary, cardiovascular, hematologic, gastrointestinal, urologic, neurologic, or psychiatric disorders
• History of severe allergic or anaphylactic reactions to human, humanized, or murine monoclonal antibodies
• Pregnant or breastfeeding, or intending to become pregnant during the study or within 4 months after the final dose of study drug
• Major surgery within 8 weeks prior to screening, or major planned surgery during the study or within 3 months after the final dose
• Positive hepatitis C virus (HCV) antibody, hepatitis B surface antigen (HBsAg), or human immunodeficiency virus (HIV) antibody test at screening
• Any serious medical condition or abnormality in clinical laboratory tests